ground on a 1974 z1 900

i recently replaced the worn battery cables on the 900 with a snazzy set fron Z1 enterprises. when i was taking the cables off i managed to snap the bolt that grounds everything off to the motor. is there another place that i can ground everything off at? there are three wires, one ground fron the rectifier, one from the electrical block, and the negative battery cable.

It's not super critical where it grounds to the motor, only that it has a good ground to the motor. Find any other good bolt in a convenient place that isnt going to effect the engine or let oil out.